In rotors of AC generators for vehicles, it is a recent trend that a larger output from a generator is required due to increase of electric load in the vehicle. Thus, a rotor is constructed such that a conductor is wound in multi-rows and multi-layers to enhance the efficiency of space. Further, in the rotor, after the conductor has been wound a predetermined number of times, resin is applied or put in drops at points where the conductor is exposed from a spool, that is, from the outer circumferential side of the outermost layer to protect the conductor from heat or foreign matter. Furthermore, to deal with the effect of a centrifugal force provided by the rotation, a protective tape is wound on the outermost circumference over the entire circumference to assure the resistance to a centrifugal force. (For example, see the Japanese Patent No. 3383143)
On the other hand, in the conventional multi-layer wound coils, a large number of through holes are provided in the tubular part, and this tubular part is immersed in varnish, or is brought in drops of varnish and impregnated, whereby the varnish is made to penetrate into deep portions of coil to cause the coil to be stabilized. (For example, see the Japanese Utility Model Publication laid-open No. 20020/1986)
However, according to such a conventional manufacturing method of a rotor, a problem exists in that even if resin is applied, for example, from the outer circumferential surface that is exposed from the spool, in the case of multi-layers, the resin will not reach into the innermost layers due to subsequent heating, and the resin is heat-cured in the state in which air is interposed between the coils, thus the coil being subjected to heat and friction. Furthermore, according to the method in which resin is made to penetrate between conductors by immersing the conductors in varnish, or by dripping and impregnating varnish into between the conductors, it is necessary for a plurality of dipping holes to be formed in the spool. Therefore, the strength required for a spool for use in rotors cannot be assured, thus there remains the possibility of deformation and breakdown. Moreover, the fact that the alignment state of conductor of multi-rows and multi-layers is changed due to such deformation of the spool, thereby the conductor being damaged, may results in failure of a power generator itself. In addition, in the case of a coil densely wound in significant numbers of layers, e.g., dozens of layers, it is considerably difficult that an impregnating varnish is uniformly run into between the coils even when the varnish is impregnated through impregnation holes. This is because, most windings, which are aligned in multi-layers and in high density, are in the state in which they are staggered to be adjacent and in close contact with each other, i.e., they are in the state of so called “traverse winding”, thus making it hard to form channels of a viscous resin penetrating into the deep layer portion (winding area deeply surrounded by the winding in the state of having been wound). In case of being wound in considerable numbers of rows, holes corresponding to the number of rows have to be formed in the tubular part of the spool. Thus, a further problem of affecting insulation properties arises in the case where an iron core is located on the inner circumferential side.
The present invention was made to solve the above-described problems, and has an object of obtaining a rotor of an electric rotating machine making it possible to suppress the loss of shape, damage and the like of a multi-layer conductor, and to ensure higher reliability even in the case that a rotor, in which multi-rows and multi-layers of winding is formed, is mounted on a vehicle and driven to rotate continuously.
A further object of the invention is to improve a cooling capability of winding, thereby enabling improved output per number of turns of windings.